Sound recording mechanism



Patented Mar. 8, 1938 I y V UNITED STATES PATENT OFFICE 2,110,223 SOUND RECORDING MECHANISM f Edward R. Harris, Los Angeles, Calif.

Application October 10, 1934, Serial No. 747.748

, 2 Claims: (01. 274-13) This invention relates to and has for a primary Fig. 2 is a sectional elevation of the same on object the provision of an improved type of sound line 2--2 of Fig. 1; recording and reproducing apparatus by means of Fig. 3 is a transverse section of the same-on which the production and reproduction of records line 3-3 of Fig. 1;

of subtantially greater length is possible as com- Fig. 4 is a fragmentary section on line 4-4 of 5 pared with records of usual length now available Fig. 2; i for commercialguse. Fig. 5 is a circuit diagram showing the electri- To this end my invention contemplates the prgcal connections between the sound record and vision of means for substantially increasing the other related units of a system;

number of groove convolutions per radial inch Fig. 6 is an enlarged elevation, partly in sec- 10 of a record by limiting the lateral thrust of the tion of a combination sound recording and reprostylus so as to provide a regular contour of the ducing unit forming a part of my invention; on groove throughout its length and thereby breakline 6-6 of Fig. 1; ing up the sound impulses into groups of relative- Fig. 7 is a section of the same .on line'I- I of ly short vibrations which are uniformly spaced Fig. '6; v e 15 apart throughout the length of the record groove. Fig. 8 is a detached elevation of the'reproducer It will be understood that in the production of on line 8-8 of Fig. 1; and

disc sound records the record grooveis formed Fig.. 9 is'an elevation of the recorder as seen on a side of a circular'disc with a succession of from line 9--9 of Fig. 6. convolutions as closely spaced apart as has been My mechanism is generally mounted upon a 20 heretofore possible, and the record is rotated at a suitablebase I at one extremity of which is rotatconstant axial speed thereby providing a variable ably mounted a turntable 2 suitably fixed to a vergroove speed. Hence, in the production or reprotical shaft 3 which is supported in spaced bearduction of the record the sound impressions in ings 4 and 5 formed on or attached to base I, as the record groove are gradually spaced farther shown in Fig. 2. A record blank 6 is adapted to apart as the stylus is moved from an inner point befrictionally held on the upper surface of table to an outer point on the record, and frequently 2 and is centered thereon in the usual manner results in distortion, inaccuracy and loss of faithas by means of a pintle I extended upwardly from fulness of reproduction. shaft 3 through a suitable aperture in the blank It is therefore, an object of my invention to or record 6. 30 provide means for rotating the record at a com A driving spindle 8 is iournalled at opposite stantly variable speed as the stylus is moved from ends of base I in rocking bearings 9 and I0 which one extreme of the groove to the other, so as to are respectively supported on the upper extremiuniformly space the sound impressions in the ties of standards II and I2 attached to or formed groove, as by means of a driving element applion the frame. An end of spindle 8 is connected cable to the record supporting table 'at a point with a speed reduction unit l3 which, in turn, is opposite the stylus and automatically adjustable connected by means of. a shaft H with a motor IS, with the stylus during a recording or reproducing whereby the spindle is rotated at a constant operation. speed.

, A further object is to provide an improved type- A driving pulley or wheel -l6 having a frictional of combination recording and reproducing unit driving surface adapted to engage the lower'surcommonly mounted for adjustment relative to face of the turntable 2 is slidably mounted on the record so that either of said elements may be spindle 8, as shown in Fig. 2. Said pulley isfixed used at will, and independently adjustable to to a sleeve 18 which has a key l9 slidably engag operating position. ing an elongated keyway 20 in a portion of spindle "5 Other important objects of invention will ap- 8' beneath the turntable 2. Said sleeve carries a pear as the description of my invention procollar 2| with an annular groove 22 on its periphgresses. 1 cry adapted to be engaged by a bifurcated voke I have shown a preferred form of apparatus 23 formed on or attached to an end of a bar 24 embodying my improvements in the accompanywhich is secured at its opposite end to a cross 5 ing drawings, subject to modification within the head 25. Bar 24 is yieldably connected with said scope of the appended claims without departing crcsshead so as not to restrict the movement of from my invention. In said drawings: pulley l8, as by means of a split connection 26 Fig. 1 is a top plan view of a sound recording the parts of which are secured together by means unit embodying my. improvements; of a bolt or screw 21, and rubber gaskets 28,18 55 may be positioned on the upper and lower sides of bar 24 and held inplace by said bolt.

It is the function of the pulley l9 to drive the turntable 2 at a variable speed to correspondto the gradual change of position of the stylus S of a recorderI-I as it cuts a sound record groove on the record 6. Accordingly, I provide a screw feed for said pulley embodying an elongated screw 29 which is externally threaded to correspond to the number of groove Iconvolutions cut or formed on the record 6. Said screw is horizontally positioned on base "I landlis' held at opposite. ends by means oi pivot screws' '99 and 91' adjustablyv held in base member l2 .and'a relatively spaced base member 92'. (See Fig. '2'.)

Obviously, as the gradual adjustmentjof Dill-.1

ley i9 must be effected withjrelat'ion to the rotation of record 9, screw 29 is driven by means of connections with turntable2. Said connections include a shaft .93 journaledin base members. H

and 92, bevel gears 94 and 95 operatively connecting shafts 9 and99randspur gears connecting shaft with screw 29, in the mannershown v inrFlg, 2, or otherwise. v. The gear ratio between shaft 9 and screw 29 is-predetermincd to correspond to the rotative speed oijturntable For instance: If the recordinghead is adapted to cut. I99 groove convolutionsper inch, -a ratio of four to one between shaft ,9 and s rews: will require forty threads per inch on screw 29, wher- I by pulley l9will .be'consta'ntly' heldlon one:

opposite head H.

Crosshead 25 is slidablysupported on base] means of a pairoflo'ngitudinal rods 99 and 8,5 I

secured at their endsto frame members l2 and-92' which are held in a pair of, oppositely extendedarms 39, ,andl], respectively. iormedjon the crosshead. A yoke 99 isformed on or attachedlto the crosshead' 29 and depends therefrom for supportinga travelling nut 39arranged1or detachv able engagement'with screw 29, as shown in Figs.

- 2 and 3.] Nut 99 but partially embraces the screw 29 and has a-depending stem 99 slidably'held in the bottom portionof. yoke 99 and carriesfa,

spring 91 adapted tocompress between the nut and the bottom 'oLportion v99, thereby tendingto hold the. nut 'yieldably in engagement with screw 29. The extended portion of stem 99 is plvotally'attached to a friction lever 92 at a point 99 which'is so arranged that the. turning of the leverwill. disengage the nut from screw 29, .or

engagev the nut with said screw, as may .be desired.

The recording and reproducing head is sup-- ported for universal "movement on the crosshead 25, as shown in Figs. 1 and 3, said crosshead', 'havingi spacedsockets and extended up-a wardly therefrom in which rods 99 and "91, respectively, aresecuredg A crosshead 99 has lat! erally formed bosses l9 and 99 thereon which are .T

slidable on rods 99 and 91. respectively. and said rods are cross connectedattheir topsby ari gid member 9|. Cros shead l9 is vertically adjustable by means oi -a screw 52 which ls-threaded through the crossheadandis rotatable in memberlil, and a hand whe l 99 is aillxed to the upper twomating members 59 and'jl, oneoi' which-issecured torod 59 and the other to and 99 on which'the head H is pivotally held. Said-recording head includes a frame composed .oi' op---' posed members 99 and. as shown in Fig. 7;be-

per end oi' screw 92 for adjustingthe crosshead.

The head H is mountedzupona rod .99 .which is secured at one end to crosshead l9 and at its other end carries a swivel fitting 99 composedot 2,110,228 v I I tween which a field coil F and a voice coil? are a system. as hereinafter described.

held and a stylus S is oscillatably' mounted in the bottom of said frame on a pivot 92.

- It will be noted by reference to Fig. '1 that the stylus S has a portion above the pivot 92 which extends through the center of the voice coil V and a continuing stem 63 between portions 69 and 99 of members 69 and GI. The frame members 99 and El are adapted to be magnetized by the energization of the field coil F and the portions and oi said members thus become poles of the magnetswliile' the stem. 93 of the stylus is an armature adapted to be vibrated between said :poles. Stem 99 extends upwardly and is tensioned between a pair 01 springs 99 and "I, or

other suitable devices carried by a central member 98, and separate adjusting screws 99 and I9 arecarried inthe frame members 99 and 9| for regulatingthe tension of said springs, for the purpose hereinafter described. On the bottom of one of the members 99 or ii a depending pin Ii isattached for providing a pilot by means of whichthe cutting depth of the record groove is limited,.said pilotbeing adaptedto engage the uppersurface 01' a record blank 9 and prevent the, stylus S from cutting beyond a predetermined depth therein. I

A reproducing head H'oi suitablevcharacter is provided in connection: with, head H and is adapted, to'be swung into and from playing posl tion while the cutting head is swung out of and into cutting" position, respectively, about theaxis i swivel 95. Said reproducer is mounted at. an angle .of .ninety degrees relative to the head- H onanarm 19 fixed to the upper part 51 of said swivel. Theunit- H -includes a fixture ll whichis. adjustablycarried on the end of arm-I9 and is held in, adjusted position by means of a set screw llprovided with an operating arm l9. The head. Hcarries the usual needle or stylus- S' and has an arm I! which is pivoted at 19 toa clevis 79 secured to'thebottom of fixture "N. as I shown in Fig.9.- Thus, the reproducing head H'" swings on the axis 19 into and i'romroperating engagementvwith .the record 9. I

- Armin which carries headH is adjustably-sccured to a fixture." bymeans of a set screw 9l' havingan operating arm 92, as shown in Fig. 8; Recording head is directly suspended from flxtux-e99, as shown in Fig. 6, by a pair of rela- I tivelyadjustable members 99 and 99 which are flanged andprovided with a frictional gasket 99 therebetwcen." Member 99 is threaded intothc bottom oifixture 99 and member 99 is heldfon member 9;! by means of'a bolt or screw 99 axial ly extendedsthrough both of said members and secured to the upper member 99. Member 94 has a depending clevis 94"between the furcation's oi'which a tubular extension91 irom frame 99 01 head H ispivotally held at 99. The end of extension 9|=-is'closed by a cap 99 through which the wires from the field and voice coils Fahd Vare extended for connection with other elements of Head H is manually adjustable as a unit on the axis of bolt 99. for the purpose hereinafter otally attached to member 99- at 9i and has a pair ofdepending I 99 extendedlrom' the periphery ofinember 99. A bracket 99 is'att'ached at its lower. extremity 99 to member 99 adjacent the bottom of fixture described, by means of an arm 99-which is pivv pins 92, 92'straddling a pin 99 is bent outwardly at its upper extremity I 99 for supporting-an adjusting screw 91 on which a nut "is adjustably held. A tension'spring 99 a so resiliently connects the lower end of screw 91 and a point I at the top of field coil F or its frame 50. Bracket 90 also has an arcuate graduated arm I0! extended over field coil F and formed concentrically with the axis 88 of frame 59 of head H. Frame 59 has an indicator arm I02 extended upwardly therefrom for adjustment over the graduated arm I0l, whereby the adjustment of the head H on its axis 88 may be gauged.

Field coil F is connected at its opposite terminals with a battery I03 by means of wires I00 and I05, as shown in Fig. 5, whereby the field coil may be continuously energized for magnetizing the pole pieces 60 and 6| of frame 59 of the recording head H. .Voice coil V is responsive to sound-impulses set up in the recording apparatus and is connected with one side I06 of an output transformer I01 by means of wires I08 and I09. Wires H0 and III lead, respectively, from the other side of transformer I01 to power tubes H3 and 4, which, in turn are connected as usual to other elements of a sound recording system, and by means of which the sound impulses from an original source are transmitted to the voice coil.

The circuit of the'voice coil being alternating in character the polarity of the armature 63 is changed and the attraction of the opposite poles of the pole pieces 60 and SI of frame 59 cause the vibration of the stylus S correspondingly under the influence of the limiting springs 66 and 61. Thus, the vibration of stylus S is more rapid and the sound impressions made thereby are more frequent and of shorter length than impressions made by the stylus without limitation of its swing. Hence, instead of a series of long impressions, each series of impressions is broken up into groups of short and closely spaced impressions on the groove of the record which are uniformly spaced throughout the length of the groove.

In operation, when a blank record disc 6 is positioned as shown on the turntable 2 the recording head H is adjusted onthe axis of swivel 55 into the position shown in Fig. 1 above the record disc, and further adjusted by turning nut 98 to the proper position for cutting a record. When in such position, the reproducing head H, as shown in Fig. 1, will be out of operative position. Records are usually made by moving the stylus from a position near the periphery of the record inwardly to a position near the axis, and

before the adjustment of the stylus to the record the surface of the record 6. The member 83- being stationary on fixture 80 and the arm 90 being pivoted on member 83, the movement of arm 90 will correspondingly rotate head H and member 84 on the axis of bolt 86 in either direction by reason of the engagement of pin 93 with one or the other oi pins 92, 02 depending from arm 90.

The adiustrnent of head H vertically relative to a record establishes the cutting depth of the groove and to this end the depth gauge MI is calibrated in thousandths or tens of thousandths of an inch so that when set for a given depth the depth of a record groove may be uniformly maintained throughout its length.

By limiting the vibration of stylus S the usual waves in a. sound groove are almost if not quite completely eliminated and I am enabled to provide a vastly greater number of groove convolutions per inch than is otherwise possible. Moreover, when recording sound on a record operated at a constant axial speed, as is customary, a single tone frequently requires several inches of groove length for recordation, whereas by rotating the record at a gradually decreasing speed from the outer extremity of a record groove to its inner extremity, a single tone requires no more groove length in an outer convolution than in an inner convolution. Thus, I am enabled to obtain in addition to substantially increased groove length, a uniformity of tones which is otherwise impossible, and a still longer and more condensed and accurate sound record on a single unit.

What I claim, is:

1. A sound recording apparatus comprising a I rotatable table for operatively supporting a record during a recording operation, a driving spindle, a sleeve splined on said spindle, a frictional wheel secured on said sleeve in frictional engagement with the under side of said turntable, a collar carried by said sleeve and provided with an an nular groove in its periphery, a cross head, a bar lying in parallel relation to said spindle and secured to said head and formed with a yoke engaging said collar in said groove, a rotatable feed screw, an arm fixed to said crosshead and lying in superposed parallel relation to said bar, a travelling nut mounted on said cross head for engagement with said feed screw, a bodily movable sound recorder supported by said arm for bodily movement therewith in operative relation to a resord supported on said rotatable table, and means whereby said feed screw is driven by said rotatable table.

2. A sound recording apparatus comprising a rotatable table for operatively supporting a record during a recording operation, a driving spindle, a sleeve splined on said spindle, a friction wheel secured on 'said sleeve in frictional engagement with the under side of said turntable, a collar carried by said-sleeve and provided with an annular groove in its periphery, a cross head, a bar substantially parallel with said spindle secured to said head and formed with a yoke engaging said collar in said groove, a rotatable feed screw, an arm fixed to said crosshead and lying in superposed parallel relation to said bar, a travelling nut mounted on said cross head for detachable engagement with said feed screw, a sound recorder, means for mounting said sound recorder on said bar forbodily movement therewith and in operative relation to a record sup- EDWARD R. HARRIS. 

